The use of a broadband network to provide services such as video services has long been adopted. FIG. 1 illustrates a schematic block diagram of some elements of such a system and the connection between them. As can be seen in this Fig. system 2 comprises a subscriber device 12 which is connected to the system via a Residential Gateway (“RG”) 10 also known as CPE. RG 10 is connected to an Access Node (AN) 6, e.g. DSLAM, as do a number of other RGs which are typically located at the same geographical neighborhood as RG 10, while the connection between RG 10 and AN 6 is done via one of AN 6 ports, shown as numeral 8 in the Fig. AN 6 is then connected to a Broadband Remote Access Server (BRAS), 4, and to the Service Provider via Broadband Network Gateway (BNG) (not shown in this Fig.). Other elements such as elements for aggregation, or subtended Access Nodes are also not shown in this Fig., but the functionality described herein which relates to basic multicast functions, is maintained also for scenarios using aggregation and subtending.
Thus, the Residential Gateway may for example be connected to the Access Node via DSL using different VLAN. One VLAN may carry the PPPoE traffic, while the multicast traffic is conveyed separately by using a different VLAN. Multicast traffic assigned to different IP multicast groups and forwarded from the BNG, is terminated at the AN. At the AN, the appropriate protocol, such as IGMP, is used to enable subscribers to join or leave respective multicast groups. Both BRAS and BNG receive the IGMP messages simultaneously. The BNG uses the information for controlling of multicast traffic, while the BRAS uses the information to control the port shaper of the ISP stream in order to avoid congestion in the Access Node.
Information about AN's port specific access rights to join a given multicast group is kept in the DSLAM, using Access Control List (“ACL”) parameters. The Access Control Lists contain the permission of a DSL port for joining and if joining to which multicast group, so that the various parameters associated with the subscriber are defined and maintained, For example, such parameters could be the number and identity of the channels that are open for the subscriber view, maximum bandwidth allocated for that subscriber, etc.
In order to enable the subscriber to receive the required services, an authentication process is held, typically between the BRAS and the subscriber. Following the authentication process (after having established the PPP session), the BRAS receives the information about permitted multicast groups from the policy server. Based upon the information received, the BRAS communicates control messages—(ACL) to the Access Node. Next, the AN enables or disables the DSL port for multicast services and configures or updates it's ACL parameters.
When the PPP session is terminated, e.g. while shutting down the subscriber's computer, when the subscriber moves with his/her laptop to another location, the DSL port at the AN is disabled and no further traffic is conveyed via the RG.